Should chrysanthemum plants be cut back to near-ground level after the flowers fade? Traditional wisdom says yes. But it really depends on where you live, says Edward Higgins of Yoder Brothers of Barberton, Ohio, a major producer of mums.
You should do it in warmer areas, but where hard, killing freezes are routine, it is better to mulch around plants and cut back in early spring, he recommends.
"I find that by not cutting back the plants, they are better able to hold mulch placed around them," says Higgins, who is Yoder's product manager.
"Also, the stems will collect a combination of leaves and twigs, developing a natural occurring mulching system, which protects the plants winter through early spring."
However, where frost is rare, such as in many parts of the South and Southwest, mums will continue to grow throughout the winter and by spring will be tall and leggy with relatively few blooms unless trimmed in the fall. They are cut back five to six inches above ground after flowering.
The theory behind mulching in colder climates is not to protect the plants from cold but to help retain soil moisture and protect against fluctuating temperatures and freeze-thaw cycles.
Not everyone agrees with mulching. It can provide breeding grounds for molds, slugs and snails. If in doubt, check with the local Cooperative Extension Service or other experts in your area. Where mulches are used, apply them at a two- to three-inch depth.
"It's important that mulched plants continue to receive good air circulation," Higgins cautions.
For that reason he likes mulches that allow plenty of air space, such as straw, evergreen boughs, pecan shells, pine needles or cocoa bean hulls. Leaves and grass clippings tend to become compacted, sodden masses, smothering the plant.
Not cutting stems from mulched plants also promotes air circulation by creating air pockets, Higgins says.
The mulch is removed gradually in the spring as new growth develops.
Higgins recommends dividing garden mums every other year when the new growth is about four inches high. He suggests discarding the old center portion of the root mass and planting the young off-shoots 18 to 24 inches apart. Water slowly and thoroughly.
Divided or not, the new shoots will need cutting and pinching several times to promote bloom and compact growth.
To most gardeners, mums are either the giant-flowered "football" types or the low-mounding, multibloom "garden" types. There are about 150 species, however.
"It's very easy to grow chrysanthemums but very difficult to grow championship ones," says Bert Konzal of Phoenix, who has been a consistent prize-winner in local shows.
He believes in changing landscape locations every third year, and he starts new ones each year from four-inch cuttings. He strips the leaves from the bottom half, dips the base in a rooting hormone and places them in a mix of half perlite and half vermiculite.
"Mums like water but not wet feet," Konzal says, so good drainage is a must. They also need a minimum of six hours of sunlight daily.
Chrysanthemum means "golden flower" in Greek, and Yoder says the top-selling color has always been yellow. It represents about 27% of sales. However, pink-lavender forms now are at 26%, followed by bronze (19%), white (15%) and red (13%).